High Quality Content by WIKIPEDIA articles! A gun port is an opening in the side of the hull of a ship, above the waterline, which allows the muzzle of artillery pieces mounted on the gun deck to fire outside. The origin of this technology is not precisely known, but can be traced back to the late 15th century, with the appearance of artillery in naval warfare. Ships featuring gun ports were said to be pierced, since the ports were cut through the hull after the construction.